Abstract

Backward masking has been proposed as a test of magnocellular sensitivity on the basis of the dual channel theory of masking. This proposal, however, faces the difficulty that the latency difference between magno- and parvocellular responses is much smaller than the typical time difference between target and mask needed for maximum backward masking. In order to make the dual channel theory consistent with magnocellular-parvocellular latency differences, it has been proposed that other factors also contribute to the time course of backward masking. This review discusses implications of this proposal for backward masking as a potential test of magnocellular sensitivity which could, if correct, have considerable clinical application in neuro-ophthalmic disorders.